In Wrath of the Lich King it is item level 166, requires level 76 and sells to vendors for 5g 94s 37c. In MoP Classic it is item level 166, requires level 76 and sells to vendors for 2g 97s 18c.
In the Appearances collection, Whale-Skin Vest is listed as Vendor. Appearance ID: 11155. No other item uses this appearance, so it is unique to Whale-Skin Vest.
Read from the World of Warcraft client build files.
How Whale-Skin Vest Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Whale-Skin Vest suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Similar Items
The 10 items nearest to Whale-Skin Vest (item level 34) in item level among Armor > Leather, Chest slot, from item level 31 to 39.
Blizzard numbers items as they are created, so the named items next to ID 44055 (44050 to 44061) were usually added in the same batch as Whale-Skin Vest: the same quest line, zone, vendor or reward set.